US20110294256A1 - Film-forming method for forming passivation film and manufacturing method for solar cell element - Google Patents
Film-forming method for forming passivation film and manufacturing method for solar cell element Download PDFInfo
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- US20110294256A1 US20110294256A1 US13/142,138 US200913142138A US2011294256A1 US 20110294256 A1 US20110294256 A1 US 20110294256A1 US 200913142138 A US200913142138 A US 200913142138A US 2011294256 A1 US2011294256 A1 US 2011294256A1
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- 238000002161 passivation Methods 0.000 title claims abstract description 83
- 238000000034 method Methods 0.000 title claims abstract description 30
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 9
- 239000000758 substrate Substances 0.000 claims abstract description 24
- 239000007789 gas Substances 0.000 claims description 47
- 238000009792 diffusion process Methods 0.000 claims description 30
- 239000004065 semiconductor Substances 0.000 claims description 21
- 230000015572 biosynthetic process Effects 0.000 claims description 17
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 12
- 229910052710 silicon Inorganic materials 0.000 claims description 7
- 239000010703 silicon Substances 0.000 claims description 7
- 229910052757 nitrogen Inorganic materials 0.000 claims description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 4
- 239000001301 oxygen Substances 0.000 claims description 4
- 229910052760 oxygen Inorganic materials 0.000 claims description 4
- 239000000969 carrier Substances 0.000 abstract description 20
- 230000006798 recombination Effects 0.000 abstract description 16
- 238000005215 recombination Methods 0.000 abstract description 16
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 7
- 229910052581 Si3N4 Inorganic materials 0.000 description 5
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 5
- 239000011248 coating agent Substances 0.000 description 5
- 238000000576 coating method Methods 0.000 description 5
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 5
- 229910052782 aluminium Inorganic materials 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 150000002500 ions Chemical class 0.000 description 4
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 238000007650 screen-printing Methods 0.000 description 3
- 229910052709 silver Inorganic materials 0.000 description 3
- 239000004332 silver Substances 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 229910052814 silicon oxide Inorganic materials 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- -1 aluminum ions Chemical class 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000012159 carrier gas Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 238000010849 ion bombardment Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 238000005268 plasma chemical vapour deposition Methods 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000002829 reductive effect Effects 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
- C23C16/50—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges
- C23C16/505—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges using radio frequency discharges
- C23C16/509—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges using radio frequency discharges using internal electrodes
- C23C16/5096—Flat-bed apparatus
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0216—Coatings
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0216—Coatings
- H01L31/02161—Coatings for devices characterised by at least one potential jump barrier or surface barrier
- H01L31/02167—Coatings for devices characterised by at least one potential jump barrier or surface barrier for solar cells
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0224—Electrodes
- H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
- H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
- H01L31/1804—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof comprising only elements of Group IV of the Periodic Table
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
- H01L31/186—Particular post-treatment for the devices, e.g. annealing, impurity gettering, short-circuit elimination, recrystallisation
- H01L31/1868—Passivation
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/547—Monocrystalline silicon PV cells
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Definitions
- This invention relates to a film-forming for a passivation film, and a manufacturing method for a solar cell element.
- a solar cell element attracting attention as a clean source of energy, is required to reduce a loss in output characteristics for increased output characteristics.
- the causes of the loss in the output characteristics of the solar cell element include optical losses, for example, a reflection loss and a transmission loss, and electrical losses, for example, the loss of carriers due to their recombination and an ohmic loss.
- Patent Document 1 discloses a solar cell element equipped with a semiconductor layer, a passivation film formed on the semiconductor layer, and an electrode, wherein an oxygen-surplus region is formed between the semiconductor layer and the passivation layer, in order to inhibit (i.e., reduce) the reflection loss and the loss of carriers due to the their recombination.
- a passivation film is formed after the surface of a semiconductor is processed with a nitrogen plasma.
- the passivation film refers to a film which functions as a protective film for protecting the semiconductor layer, and also functions as an anti-reflection coating film.
- the challenge for the present invention is, therefore, to solve the above-mentioned problem of the conventional technology, thereby providing a film-forming method and for forming a passivation film for a solar cell element, the passivation film being capable of sufficiently inhibiting the loss of carriers due to their recombination.
- the present invention is also directed to providing a method for manufacturing a solar cell element using the same.
- the film-forming method of the present invention is a film-forming method which comprises introducing a film-forming gas containing silicon and at least one species selected from nitrogen and oxygen, and applying a high frequency voltage from a high frequency power source, with a shower plate for introduction of the film-forming gas serving as a discharge electrode, to generate a plasma, thereby forming a passivation film on a solar cell element provided with a diffusion layer, and further comprising applying a low frequency voltage from a low frequency power source to the shower plate or the diffusion layer during film formation, thereby forming the passivation film on the diffusion layer.
- the film is formed on the film-forming object by applying the high frequency voltage from the high frequency power source during film formation, while further applying the low frequency voltage to the shower plate or the film-forming object from the low frequency power source.
- the film quality of the film namely the film density and the fixed charge density in film.
- the passivation film be formed on the diffusion layer. The reason is that the film-forming speed is increased by forming the passivation film for a solar cell element on the film-forming object while applying the low frequency voltage to the shower plate.
- the inputting power of the low frequency power source is preferably 14 to 37% of the inputting power of the high frequency power source.
- film quality is further improved, and the loss of carriers due to their recombination can be fully inhibited.
- a method for manufacturing a solar cell element according to the present invention comprises a diffusion layer formation step of forming a diffusion layer on a surface of a semiconductor substrate, a passivation film formation step of forming a passivation film on the diffusion layer, and an electrode formation step of forming a grid electrode on the passivation film, and then further forming a back electrode on the other surface of the semiconductor substrate, followed by heating, to connect the grid electrode to the diffusion layer, and is characterized in that the passivation film formation step introduces a film-forming gas containing silicon and at least one species selected from nitrogen and oxygen, and applies a high frequency voltage from a high frequency power source, with a shower plate for introduction of the film-forming gas serving as a discharge electrode, and also applies a low frequency voltage from a low frequency power source to the shower plate or the semiconductor substrate having the diffusion layer formed thereon, to generate a plasma, thereby forming the passivation film on the diffusion layer.
- the passivation film formation step introduces a film-forming gas containing silicon and at
- the high frequency voltage is applied from the high frequency power source, and the low frequency voltage is applied from the low frequency power source to the shower plate or the semiconductor substrate having the diffusion layer formed thereon.
- the film quality of the resulting passivation film is satisfactory, and the loss of carriers due to their recombination in a solar cell element can be inhibited.
- the excellent effect of improving output characteristics can be exhibited.
- the manufacturing method for a solar cell element of the present invention the film quality of the passivation film is satisfactory, so that the loss of carriers due to their recombination can be inhibited. This produces the excellent effect of improving output characteristics.
- FIG. 1 is a schematic sectional view of a solar cell element.
- FIG. 2 is a schematic view of a film-forming device according to the present embodiment.
- FIG. 3 is a schematic view of a film-forming device according to another embodiment.
- FIG. 4 is a graph showing the results of Examples 1 to 4.
- FIG. 5 is a graph showing the results of Example 5.
- FIG. 6 is a graph showing the results of Example 6.
- FIG. 7 is a graph showing the results of Examples 7 to 10.
- a solar cell element 1 which is a unit cell of a solar cell, has a p-type semiconductor substrate 11 .
- the p-type semiconductor substrate 11 has irregularities (not shown) provided on its surfaces by texture etching.
- An n-type diffusion layer 12 is provided on one surface of the p-type semiconductor substrate 11 .
- the n-type diffusion layer 12 is formed, for example, by coating the surface of the p-type semiconductor substrate 11 with a paint containing phosphorus, and then heat-treating the coating.
- a passivation layer 13 is formed on the surface of the n-type diffusion layer 12 .
- the passivation layer 13 comprises a film (passivation film) which is one of a silicon nitride film (SiN), a silicon oxide film (SiO), and a silicon oxynitride film (SiON).
- This passivation film is formed by a film-forming method of the present embodiment to be described later. Since the passivation film is formed by the film-forming method of the present embodiment, its film quality is improved. As a result, the lifetime of carriers, which is named as an indicator of whether the recombination of carriers is suppressed, is lengthened. That is, the loss of carriers is inhibited. Thus, the output efficiency in the solar cell element 1 is increased.
- the passivation layer 13 is provided with a grid electrode 14 .
- the grid electrode 14 is provided on the passivation film, and then heated to pierce the passivation film and connect to the n-type diffusion layer 12 .
- a BSF layer 15 and a back electrode layer 16 are provided in this order.
- the BSF layer 15 is a high concentration p-type diffusion layer, and the BSF layer is formed simultaneously with the formation of the back electrode layer 16 .
- the back electrode layer 16 consists of a first back electrode layer 16 a which functions as a p-type impurity supply source for a p + layer and as a grid electrode, and a second back electrode layer 16 b which functions as a current collecting electrode for current collection from the entire back of the solar cell.
- the first back electrode layer 16 a is formed by coating aluminum only or a paste containing aluminum, followed by baking, so that aluminum ions diffuse into the element to provide the p-type impurity supply source for the p + layer.
- the second back electrode layer 16 b is composed of low resistance silver.
- a film-forming device 2 which carries out a film-forming method for forming the passivation film to be used in this solar cell element.
- a film-forming device 2 is designed to form a passivation film by performing the plasma CVD method.
- the film-forming device 2 is equipped with a vacuum chamber 21 which can hold a desired vacuum state.
- the vacuum chamber 21 is provided with a mounting stand 22 equipped with a heating device (not shown).
- a film-forming object S which comprises a plurality of the p-type semiconductor substrates 11 arranged side by side and each having the n-type diffusion layer 12 formed thereon, is mounted on the mounting stand 22 .
- the heating device can adjust this film-forming object S to a desired substrate temperature during film formation.
- a shower plate 23 is provided to face the film-forming object S.
- a gas introduction means 24 for introducing a film-forming gas is connected to the shower plate 23 .
- the gas introduction means 24 in the present embodiment, is configured to be capable of introducing three gases, for example.
- gas sources 24 a , 24 b , 24 c having different gases in the present embodiment, SiH 4 , NH 3 , N 2 ) sealed up therein, respectively, are connected to a gas introduction pipe 24 d via valves 24 e .
- the gas introduction means 24 is configured to be capable of introducing the three gases, but may be configured to have six gas sources, for example, and select a gas in accordance with the film constitution so that the selected gas can be introduced in accordance with the desired film constitution.
- a high frequency power source 25 is connected to the shower plate 23 so as to apply a high frequency voltage to the shower plate 23 .
- the shower plate 23 functions as a gas inlet for introducing the film-forming gas into the vacuum chamber 21 uniformly, and also functions as a discharge electrode upon application of the high frequency voltage.
- the mounting stand 22 is provided with a low frequency power source 26 so that a low frequency voltage can be applied toward the film-forming object S. That is, the film-forming device 2 of the present embodiment is configured to be capable of applying voltages of different frequencies from the high frequency power source 25 and the low frequency power source 26 during film formation, thereby forming a plasma to render film formation possible.
- the film-forming method using the film-forming device 2 will be described.
- the film-forming object S is mounted on the mounting stand 22 within the vacuum chamber 21 .
- the interior of the vacuum chamber 21 is brought to a desired vacuum state.
- the film-forming gas is introduced from the gas introduction means 24 , and voltages are applied from the high frequency power source 25 and the low frequency power source 26 to generate a plasma, thereby forming a passivation film on the film-forming object S.
- the passivation film is formed, with the voltages being applied from the high frequency power source 25 and the low frequency power source 26 , whereby the passivation film of a satisfactory film quality can be formed. Consequently, the lifetime of the solar cell element 1 using this film can be increased.
- SiH 4 is introduced as a Si-containing gas, and one gas or more gases selected from NH 3 , N 2 and NF 3 is or are introduced as a N-containing gas, in forming a silicon nitride film as the passivation film.
- SiH 4 is introduced as a Si-containing gas, and one gas or more gases selected from N 2 O and O 2 is or are introduced as an O-containing gas.
- SiH 4 is introduced as a Si-containing gas
- one or more gases selected from NH 3 , N 2 and NF 3 are introduced as a N-containing gas
- one or more gases selected from N 2 O and O 2 are introduced as an O-containing gas.
- an inert gas for example, an Ar gas
- the flow rate of each gas is 1500 to 1600 sccm for SiH 4 , 3000 to 6000 sccm for NH 3 , and 4000 to 7000 sccm for N 2 .
- the high frequency power source 25 may be one which can apply a voltage at a high frequency of 13.56 to 27.12 MHz, while the low frequency power source 26 may be one which can apply a voltage at a low frequency of 20 to 400 kHz.
- the inputting power of the high frequency power source 25 is 1000 to 3500 W.
- the inputting power of the low frequency power source 26 is 300 to 2000 W, preferably 500 to 1250 W.
- the inputting power of the low frequency power source 26 be about 14 to 37%, preferably about 26 to 34%, of the inputting power of the high frequency power source 25 .
- a passivation film of better film quality can be formed, whereby the lifetime of the solar cell element can be increased. As a result, the output characteristics of the solar cell element can be improved.
- the passivation film formed under the above-described film-forming conditions requires a film-forming time of 25 seconds, has a film thickness of 800 ⁇ , and has a refractive index of 1.9 to 2.2.
- the lifetime of the solar cell element 1 provided with this film is 1,000 ⁇ s or more, and may be 2,500 ⁇ s or even more. Thus, it is seen that a loss in carriers due to their recombination is inhibited.
- FIG. 3 is a schematic view showing an alternative embodiment of the film-forming device.
- a low frequency power source 26 is provided for a shower plate 23 provided with a high frequency power source 25 .
- the low frequency power source 26 is provided on the side of the shower plate 23 as noted above, the effect can be obtained that a film of the same satisfactory film quality as that by the aforementioned film-forming device 2 can be formed under the same film-forming conditions.
- the different film-forming device 3 shown in FIG. 3 is advantageous in that its film-forming rate or speed is higher than that of the film-forming device 2 shown in FIG. 2 .
- the present invention has the low frequency power source provided for either the shower plate 23 which functions as a cathode electrode contributing to the generation of plasma within the vacuum chamber 21 , or the mounting stand 22 which functions as an anode electrode.
- the film quality of the passivation film can be improved, whereby the loss of carriers due to their recombination in the solar cell element is inhibited.
- the passivation film has satisfactory film quality, for example, as the solar cell element 1 , concretely, high film density and high fixed charge density in the film.
- the charge of ions excited by the low frequency voltage is added to the charge of the plasma excited by the high frequency voltage, whereby the potential difference between the substrate and the plasma, namely, sheath electric field, can be increased.
- ion energy incident on the surface of the substrate can be increased.
- the passivation film is formed more densely (high film density), and the charge present in the passivation film also increases. Consequently, the passivation film has a high positive fixed charge density.
- the low frequency power source for applying a low frequency voltage is connected to the shower plate or the mounting portion, so that the film quality of the resulting film (i.e., film density and fixed charge density or concentration in film) is improved.
- the use of the resulting film for example, as a passivation film for a solar cell element makes it possible to fully inhibit the loss of carriers due to their recombination in accordance with the improvement of the film quality.
- the film-forming rate or speed becomes high because the high frequency power source and the low frequency power source are connected to the shower plate.
- a passivation film was formed using the film-forming device 2 shown in FIG. 2 , whereafter a solar cell element was prepared.
- an n-type diffusion layer 12 was formed on a surface of a 220 ⁇ m thick p-type semiconductor substrate 11 (156 mm ⁇ 156 mm) of monocrystal silicon having irregularities provided on the surface by texture etching. A plurality of the so treated substrates 11 were arranged side by side on a tray to provide a film-forming object S.
- the film-forming object S was carried into the film-forming device 2 shown in FIG. 2 , and a passivation film comprising a silicon nitride film was formed under the following conditions: Substrate temperature: 350° C., SiH 4 flow rate: 1500 sccm, NH 3 flow rate: 5000 sccm, N 2 flow rate: 6000 sccm, frequency of the high frequency power source 25 : 13.56 MHz, inputting power of the high frequency power source 25 : 1500 W, pressure within the vacuum chamber: 100 Pa, E/S: 14 mm, frequency of the low frequency power source: 300 kHz, inputting power of the low frequency power source 26 : 500 W.
- the film-forming object S having the passivation film formed thereon was taken out of the film-forming device 2 , and a silver paste was coated in a lattice pattern on the passivation film to a thickness of 10 ⁇ m by the screen printing method. Then, the coating was dried for 10 minutes at 150° C. to form a grid electrode film.
- a silver paste was coated on the back to a thickness of 10 ⁇ m by the screen printing method, followed by drying for 10 minutes at 150° C., to form a first back electrode film.
- an aluminum paste was coated to a thickness of 10 ⁇ m by the screen printing method, followed by drying for 10 minutes at 150° C., to form a second back electrode film.
- the film-forming object S was heat-treated for 3 seconds at 750° C. to convert the first back electrode film and the second back electrode film into a first back electrode layer 16 a and a second back electrode layer 16 b , respectively.
- a BSF layer 15 was formed between the back electrode layer 16 and the p-type semiconductor substrate 11 .
- the grid electrode film pierced the passivation film to come into contact with the n-type diffusion layer 12 , forming a grid electrode 14 .
- a solar cell element 1 having the passivation film formed as a passivation layer 13 by the film-forming device 2 was obtained.
- a solar cell element 1 was produced under exactly the same conditions as those in Example 1, except that the inputting power of the low frequency power source 26 was set at 1000 W.
- a solar cell element 1 was produced under exactly the same conditions as those in Example 1, except that a passivation film was formed using the film-forming device 3 shown in FIG. 3 .
- a solar cell element 1 was produced under exactly the same conditions as those in Example 3, except that the inputting power of the low frequency power source 26 was set at 1000 W.
- the lifetimes of the solar cell elements 1 obtained in Examples 1 to 4 were measured with a lifetime measuring device (produced by KOBELCO Research Institute, Inc.) using the microwave photoconductivity decay method. The results of the measurements are shown in FIG. 4 .
- the device shown in FIG. 2 and the device shown in FIG. 3 both presented lifetimes of almost 2000 ⁇ s.
- the film-forming device 2 shown in FIG. 2 and the film-forming device 3 shown in FIG. 3 both presented lifetimes in excess of 2000 ⁇ s, but the lifetime was slightly higher with the film-forming device 3 shown in FIG. 3 .
- the lifetime of a solar cell element is of the order of 1000 ⁇ s, so that the results on the film-forming device 2 shown in FIG. 2 and the film-forming device 3 shown in FIG. 3 were both improved, i.e., lengthened, as compared with the value of the conventional solar cell element.
- the high frequency power source 25 and the low frequency power source 26 were provided and, with a high frequency voltage and a low frequency voltage being applied, the passivation film was formed. Consequently, a passivation film of satisfactory film quality could be formed, whereby the lifetime of the solar cell element could be increased.
- passivation films were formed using the film-forming device 3 shown in FIG. 3 , with the inputting power of the low frequency power source 26 being varied, whereafter solar cell elements were prepared. That is, solar cell elements 1 were prepared under exactly the same conditions as those in Example 3, except that the inputting powers of the low frequency power source were set at 0 W, 500 W and 1000 W, respectively, in forming the passivation films.
- the lifetimes of the resulting solar cell elements were measured by the microwave photoconductivity decay method. The results of the measurements are shown in FIG. 5 .
- the lifetime was the longest, exceeding 2500 ⁇ s.
- the lifetime was longer when the inputting power of the low frequency power source 26 was 1000 W, than when it was zero, namely, when the low frequency power source 26 was not provided; that is, the lifetime was 2000 ⁇ s.
- the inputting power of the low frequency power source 26 was 250 to 1000 W, namely, when the inputting power of the low frequency power source 26 was about 16 to 67% of the inputting power of the high frequency power source 25 , the lifetime exceeded 2000 ⁇ s.
- the lifetime exceeded 2500 ⁇ s, providing better results.
- passivation films were formed, and solar cell elements were produced, under the same conditions as those in Example 3, except that the inputting power of the high frequency power source 25 was changed, and the inputting power of the low frequency power source 26 was changed. That is, solar cell elements 1 were prepared under exactly the same conditions as those in Example 3, except that the inputting power of the high frequency power source 25 was set at 3500 W, while the inputting powers of the low frequency power source 26 were set at 500 W, 1000 W, 1500 W and 1900 W, respectively.
- the lifetimes of the solar cell elements 1 obtained in Example 6 were measured by the microwave photoconductivity decay method. The results of the measurements are shown in FIG. 6 .
- the lifetime was the longest, exceeding 3000 ⁇ s.
- the inputting powers of the low frequency power source 26 were 1500 W and 1900 W, the lifetimes were of the order of 1000 ⁇ s. Based on these results, when the inputting power of the low frequency power source 26 was 500 to 1500 W, namely, when the inputting power of the low frequency power source 26 was about 14 to 37% of the inputting power of the high frequency power source 25 , the lifetime exceeded 2000 ⁇ s.
- the lifetime exceeded 2500 ⁇ s, providing better results.
- Examples 5 and 6 show that the inputting power of the low frequency power source 26 was preferably about 14 to 37% of the inputting power of the high frequency power source 25 , and that the inputting power of the low frequency power source 26 was particularly preferably about 26 to 34% of the inputting power of the high frequency power source 25 .
- a passivation film comprising a silicon nitride film was formed in exactly the same manner as in Example 1, except that the following changes were made: SiH 4 flow rate: 3000 sccm, NH 3 flow rate: 1800 sccm, and N 2 flow rate: 2500 sccm.
- a passivation film comprising a silicon nitride film was formed in exactly the same manner as in Example 7, except that the inputting power of the low frequency power source 26 was changed to 1000 W.
- film formation was performed under exactly the same conditions as in Example 7, except that the film-forming device 3 was used. Then, the thickness of the film was measured.
- film formation was performed under exactly the same conditions as in Example 8, except that the film-forming device 3 was used. Then, the thickness of the film was measured.
- the film obtained in each of the Examples was measured for film thickness with an ellipsometer (ESM-3000AT, ULVAC, Inc.). The measured film thickness was divided by the film-forming time to determine the film-forming speed. The results are shown in FIG. 7 .
- the film-forming speed was higher when the film was formed using the film-forming device 3 than when the film was formed using the film-forming device 2 .
- a high frequency voltage and a low frequency voltage were preferably applied to the shower plate 23 , as in the film-forming device 3 .
- the passivation film obtained by the film-forming method and the film-forming device in the present embodiment can be utilized, for example, as a passivation film of an organic EL device or the like, but is preferably used as a passivation film of a solar cell element, as in the present embodiment.
- the present invention can be utilized in the field of production of a solar cell element.
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Abstract
Description
- This application is a National Stage entry of International Application No. PCT/JP2009/071767, filed on Dec. 28, 2009, which claims priority to Japanese Patent Application 2008-335051, filed Dec. 26, 2008. The disclosure of the prior application is hereby incorporated in its entirety by reference.
- This invention relates to a film-forming for a passivation film, and a manufacturing method for a solar cell element.
- A solar cell element, attracting attention as a clean source of energy, is required to reduce a loss in output characteristics for increased output characteristics. The causes of the loss in the output characteristics of the solar cell element include optical losses, for example, a reflection loss and a transmission loss, and electrical losses, for example, the loss of carriers due to their recombination and an ohmic loss.
-
Patent Document 1, for example, discloses a solar cell element equipped with a semiconductor layer, a passivation film formed on the semiconductor layer, and an electrode, wherein an oxygen-surplus region is formed between the semiconductor layer and the passivation layer, in order to inhibit (i.e., reduce) the reflection loss and the loss of carriers due to the their recombination. For this purpose, a passivation film is formed after the surface of a semiconductor is processed with a nitrogen plasma. The passivation film refers to a film which functions as a protective film for protecting the semiconductor layer, and also functions as an anti-reflection coating film. -
- Patent Document 1: JP-A-2005-159171 (
claim 1, claim 7, etc.) - However, even when the oxygen-surplus region is formed by forming the passivation film after nitrogen plasma processing, the problem is posed that the loss of carriers due to their recombination in the solar cell element cannot be fully inhibited (i.e., reduced), if the film quality of the passivation film itself is not satisfactory.
- The challenge for the present invention is, therefore, to solve the above-mentioned problem of the conventional technology, thereby providing a film-forming method and for forming a passivation film for a solar cell element, the passivation film being capable of sufficiently inhibiting the loss of carriers due to their recombination. The present invention is also directed to providing a method for manufacturing a solar cell element using the same.
- The film-forming method of the present invention is a film-forming method which comprises introducing a film-forming gas containing silicon and at least one species selected from nitrogen and oxygen, and applying a high frequency voltage from a high frequency power source, with a shower plate for introduction of the film-forming gas serving as a discharge electrode, to generate a plasma, thereby forming a passivation film on a solar cell element provided with a diffusion layer, and further comprising applying a low frequency voltage from a low frequency power source to the shower plate or the diffusion layer during film formation, thereby forming the passivation film on the diffusion layer. In the film-forming method of the present invention, the film is formed on the film-forming object by applying the high frequency voltage from the high frequency power source during film formation, while further applying the low frequency voltage to the shower plate or the film-forming object from the low frequency power source. By so doing, the film quality of the film, namely the film density and the fixed charge density in film, is improved. When the resulting film is used, for example, as a passivation film for a solar cell element, the loss of carriers due to their recombination can be fully inhibited in accordance with an improvement in film quality.
- It is preferred that with the low frequency power source applying the low frequency voltage to the shower plate, the passivation film be formed on the diffusion layer. The reason is that the film-forming speed is increased by forming the passivation film for a solar cell element on the film-forming object while applying the low frequency voltage to the shower plate.
- Moreover, the inputting power of the low frequency power source is preferably 14 to 37% of the inputting power of the high frequency power source. Within this range, film quality is further improved, and the loss of carriers due to their recombination can be fully inhibited.
- A method for manufacturing a solar cell element according to the present invention comprises a diffusion layer formation step of forming a diffusion layer on a surface of a semiconductor substrate, a passivation film formation step of forming a passivation film on the diffusion layer, and an electrode formation step of forming a grid electrode on the passivation film, and then further forming a back electrode on the other surface of the semiconductor substrate, followed by heating, to connect the grid electrode to the diffusion layer, and is characterized in that the passivation film formation step introduces a film-forming gas containing silicon and at least one species selected from nitrogen and oxygen, and applies a high frequency voltage from a high frequency power source, with a shower plate for introduction of the film-forming gas serving as a discharge electrode, and also applies a low frequency voltage from a low frequency power source to the shower plate or the semiconductor substrate having the diffusion layer formed thereon, to generate a plasma, thereby forming the passivation film on the diffusion layer. In the method for manufacturing a solar cell element according to the present invention, the high frequency voltage is applied from the high frequency power source, and the low frequency voltage is applied from the low frequency power source to the shower plate or the semiconductor substrate having the diffusion layer formed thereon. By so doing, the film quality of the passivation film, namely the film density and the fixed charge density in the film, can be rendered high, whereby the loss of carriers due to their recombination in the solar cell element can be fully inhibited.
- According to the film-forming device for forming a passivation film and the film-forming method for forming a passivation film in the present invention, the film quality of the resulting passivation film is satisfactory, and the loss of carriers due to their recombination in a solar cell element can be inhibited. Thus, the excellent effect of improving output characteristics can be exhibited. According to the manufacturing method for a solar cell element of the present invention, the film quality of the passivation film is satisfactory, so that the loss of carriers due to their recombination can be inhibited. This produces the excellent effect of improving output characteristics.
-
FIG. 1 is a schematic sectional view of a solar cell element. -
FIG. 2 is a schematic view of a film-forming device according to the present embodiment. -
FIG. 3 is a schematic view of a film-forming device according to another embodiment. -
FIG. 4 is a graph showing the results of Examples 1 to 4. -
FIG. 5 is a graph showing the results of Example 5. -
FIG. 6 is a graph showing the results of Example 6. -
FIG. 7 is a graph showing the results of Examples 7 to 10. - First of all, a solar cell element will be described. A
solar cell element 1, which is a unit cell of a solar cell, has a p-type semiconductor substrate 11. The p-type semiconductor substrate 11 has irregularities (not shown) provided on its surfaces by texture etching. An n-type diffusion layer 12 is provided on one surface of the p-type semiconductor substrate 11. The n-type diffusion layer 12 is formed, for example, by coating the surface of the p-type semiconductor substrate 11 with a paint containing phosphorus, and then heat-treating the coating. Apassivation layer 13 is formed on the surface of the n-type diffusion layer 12. - The
passivation layer 13 comprises a film (passivation film) which is one of a silicon nitride film (SiN), a silicon oxide film (SiO), and a silicon oxynitride film (SiON). This passivation film is formed by a film-forming method of the present embodiment to be described later. Since the passivation film is formed by the film-forming method of the present embodiment, its film quality is improved. As a result, the lifetime of carriers, which is named as an indicator of whether the recombination of carriers is suppressed, is lengthened. That is, the loss of carriers is inhibited. Thus, the output efficiency in thesolar cell element 1 is increased. - The
passivation layer 13 is provided with agrid electrode 14. Thegrid electrode 14 is provided on the passivation film, and then heated to pierce the passivation film and connect to the n-type diffusion layer 12. On the other surface of the p-type semiconductor substrate 11, aBSF layer 15 and aback electrode layer 16 are provided in this order. TheBSF layer 15 is a high concentration p-type diffusion layer, and the BSF layer is formed simultaneously with the formation of theback electrode layer 16. Theback electrode layer 16 consists of a firstback electrode layer 16 a which functions as a p-type impurity supply source for a p+ layer and as a grid electrode, and a secondback electrode layer 16 b which functions as a current collecting electrode for current collection from the entire back of the solar cell. The firstback electrode layer 16 a is formed by coating aluminum only or a paste containing aluminum, followed by baking, so that aluminum ions diffuse into the element to provide the p-type impurity supply source for the p+ layer. The secondback electrode layer 16 b is composed of low resistance silver. - An explanation will be offered for a film-forming device which carries out a film-forming method for forming the passivation film to be used in this solar cell element. A film-forming
device 2 is designed to form a passivation film by performing the plasma CVD method. The film-formingdevice 2 is equipped with avacuum chamber 21 which can hold a desired vacuum state. Thevacuum chamber 21 is provided with a mountingstand 22 equipped with a heating device (not shown). A film-forming object S, which comprises a plurality of the p-type semiconductor substrates 11 arranged side by side and each having the n-type diffusion layer 12 formed thereon, is mounted on the mountingstand 22. The heating device can adjust this film-forming object S to a desired substrate temperature during film formation. - On the ceiling surface of the
vacuum chamber 21, ashower plate 23 is provided to face the film-forming object S. A gas introduction means 24 for introducing a film-forming gas is connected to theshower plate 23. The gas introduction means 24, in the present embodiment, is configured to be capable of introducing three gases, for example. In the gas introduction means 24,gas sources gas introduction pipe 24 d viavalves 24 e. In the present embodiment, the gas introduction means 24 is configured to be capable of introducing the three gases, but may be configured to have six gas sources, for example, and select a gas in accordance with the film constitution so that the selected gas can be introduced in accordance with the desired film constitution. - Moreover, a high
frequency power source 25 is connected to theshower plate 23 so as to apply a high frequency voltage to theshower plate 23. Thus, theshower plate 23 functions as a gas inlet for introducing the film-forming gas into thevacuum chamber 21 uniformly, and also functions as a discharge electrode upon application of the high frequency voltage. - In the present embodiment, moreover, the mounting
stand 22 is provided with a lowfrequency power source 26 so that a low frequency voltage can be applied toward the film-forming object S. That is, the film-formingdevice 2 of the present embodiment is configured to be capable of applying voltages of different frequencies from the highfrequency power source 25 and the lowfrequency power source 26 during film formation, thereby forming a plasma to render film formation possible. - The film-forming method using the film-forming
device 2 will be described. First, the film-forming object S is mounted on the mountingstand 22 within thevacuum chamber 21. Then, the interior of thevacuum chamber 21 is brought to a desired vacuum state. The film-forming gas is introduced from the gas introduction means 24, and voltages are applied from the highfrequency power source 25 and the lowfrequency power source 26 to generate a plasma, thereby forming a passivation film on the film-forming object S. In the present embodiment, the passivation film is formed, with the voltages being applied from the highfrequency power source 25 and the lowfrequency power source 26, whereby the passivation film of a satisfactory film quality can be formed. Consequently, the lifetime of thesolar cell element 1 using this film can be increased. - As the film-forming gas, SiH4 is introduced as a Si-containing gas, and one gas or more gases selected from NH3, N2 and NF3 is or are introduced as a N-containing gas, in forming a silicon nitride film as the passivation film. In forming a silicon oxide film as the passivation film, SiH4 is introduced as a Si-containing gas, and one gas or more gases selected from N2O and O2 is or are introduced as an O-containing gas. When the silicon oxynitride film is to be formed, SiH4 is introduced as a Si-containing gas, one or more gases selected from NH3, N2 and NF3 are introduced as a N-containing gas, and one or more gases selected from N2O and O2 are introduced as an O-containing gas. Furthermore, an inert gas, for example, an Ar gas, may be incorporated as a carrier gas into the film-forming gas. When the SiN film is to be used as the passivation film, for example, the flow rate of each gas is 1500 to 1600 sccm for SiH4, 3000 to 6000 sccm for NH3, and 4000 to 7000 sccm for N2.
- The high
frequency power source 25 may be one which can apply a voltage at a high frequency of 13.56 to 27.12 MHz, while the lowfrequency power source 26 may be one which can apply a voltage at a low frequency of 20 to 400 kHz. - The inputting power of the high
frequency power source 25 is 1000 to 3500 W. The inputting power of the lowfrequency power source 26 is 300 to 2000 W, preferably 500 to 1250 W. Moreover, it is preferred that the inputting power of the lowfrequency power source 26 be about 14 to 37%, preferably about 26 to 34%, of the inputting power of the highfrequency power source 25. When the inputting power of the lowfrequency power source 26 is within this range relative to the inputting power of the highfrequency power source 25, a passivation film of better film quality can be formed, whereby the lifetime of the solar cell element can be increased. As a result, the output characteristics of the solar cell element can be improved. - Other film-forming conditions for the passivation film are as follows: Substrate temperature: 380 to 420° C., pressure within vacuum chamber: 100 to 250 Pa, substrate-to-shower plate distance (E/S): 12 to 25 mm.
- The passivation film formed under the above-described film-forming conditions requires a film-forming time of 25 seconds, has a film thickness of 800 Å, and has a refractive index of 1.9 to 2.2. The lifetime of the
solar cell element 1 provided with this film is 1,000 μs or more, and may be 2,500 μs or even more. Thus, it is seen that a loss in carriers due to their recombination is inhibited. - Next, another embodiment of the film-forming
device 2 will be described usingFIG. 3 .FIG. 3 is a schematic view showing an alternative embodiment of the film-forming device. In a film-formingdevice 3 according to this alternative embodiment, a lowfrequency power source 26 is provided for ashower plate 23 provided with a highfrequency power source 25. Even when the lowfrequency power source 26 is provided on the side of theshower plate 23 as noted above, the effect can be obtained that a film of the same satisfactory film quality as that by the aforementioned film-formingdevice 2 can be formed under the same film-forming conditions. Furthermore, the different film-formingdevice 3 shown inFIG. 3 is advantageous in that its film-forming rate or speed is higher than that of the film-formingdevice 2 shown inFIG. 2 . That is, the present invention has the low frequency power source provided for either theshower plate 23 which functions as a cathode electrode contributing to the generation of plasma within thevacuum chamber 21, or the mountingstand 22 which functions as an anode electrode. By applying a low frequency voltage to one of them while applying a high frequency voltage by the high frequency power source, the film quality of the passivation film can be improved, whereby the loss of carriers due to their recombination in the solar cell element is inhibited. - With a plasma which has hitherto been formed by applying only a voltage of a high frequency (13.56 MHz to 27.12 MHz), plasma density and plasma potential have been determined by conditions for generation of plasma, such as the type of the gas, the inputting power, and the electrode-to-electrode distance. Under the film-forming conditions involving a high speed of 30 Å/s or higher, film quality necessary for the solar cell element, represented by film density and fixed charge in the film, has not been successfully obtained. With the conventional passivation film, therefore, the loss of carriers due to their recombination has failed to be sufficiently inhibited.
- With the present embodiment, on the other hand, voltages of different frequencies, i.e., a high frequency and a low frequency, are superposed and applied to form the passivation film, so that the passivation film has satisfactory film quality, for example, as the
solar cell element 1, concretely, high film density and high fixed charge density in the film. In detail, the charge of ions excited by the low frequency voltage is added to the charge of the plasma excited by the high frequency voltage, whereby the potential difference between the substrate and the plasma, namely, sheath electric field, can be increased. As a result, ion energy incident on the surface of the substrate can be increased. With the increase in the ion energy, ion bombardment of the substrate surface by the incident ions is also enhanced. Thus, the passivation film is formed more densely (high film density), and the charge present in the passivation film also increases. Consequently, the passivation film has a high positive fixed charge density. - Since such a passivation film is formed, positive carriers (holes) moved toward the interface of the passivation film are repelled and pushed back. Thus, hole density can be decreased even at the interface with a high defect density. Hence, the recombination of carriers can be suppressed, and the lifetime of carriers can be lengthened.
- In the film-forming device of the each embodiment, the low frequency power source for applying a low frequency voltage is connected to the shower plate or the mounting portion, so that the film quality of the resulting film (i.e., film density and fixed charge density or concentration in film) is improved. The use of the resulting film, for example, as a passivation film for a solar cell element makes it possible to fully inhibit the loss of carriers due to their recombination in accordance with the improvement of the film quality. And, the film-forming rate or speed becomes high because the high frequency power source and the low frequency power source are connected to the shower plate.
- Hereinafter, the present invention will be described in more detail by Examples.
- In the present example, a passivation film was formed using the film-forming
device 2 shown inFIG. 2 , whereafter a solar cell element was prepared. - First, an n-
type diffusion layer 12 was formed on a surface of a 220 μm thick p-type semiconductor substrate 11 (156 mm×156 mm) of monocrystal silicon having irregularities provided on the surface by texture etching. A plurality of the so treatedsubstrates 11 were arranged side by side on a tray to provide a film-forming object S. - Then, the film-forming object S was carried into the film-forming
device 2 shown inFIG. 2 , and a passivation film comprising a silicon nitride film was formed under the following conditions: Substrate temperature: 350° C., SiH4 flow rate: 1500 sccm, NH3 flow rate: 5000 sccm, N2 flow rate: 6000 sccm, frequency of the high frequency power source 25: 13.56 MHz, inputting power of the high frequency power source 25: 1500 W, pressure within the vacuum chamber: 100 Pa, E/S: 14 mm, frequency of the low frequency power source: 300 kHz, inputting power of the low frequency power source 26: 500 W. - Then, the film-forming object S having the passivation film formed thereon was taken out of the film-forming
device 2, and a silver paste was coated in a lattice pattern on the passivation film to a thickness of 10 μm by the screen printing method. Then, the coating was dried for 10 minutes at 150° C. to form a grid electrode film. - Then, a silver paste was coated on the back to a thickness of 10 μm by the screen printing method, followed by drying for 10 minutes at 150° C., to form a first back electrode film. Then, an aluminum paste was coated to a thickness of 10 μm by the screen printing method, followed by drying for 10 minutes at 150° C., to form a second back electrode film. Finally, the film-forming object S was heat-treated for 3 seconds at 750° C. to convert the first back electrode film and the second back electrode film into a first
back electrode layer 16 a and a secondback electrode layer 16 b, respectively. Moreover, aBSF layer 15 was formed between theback electrode layer 16 and the p-type semiconductor substrate 11. The grid electrode film pierced the passivation film to come into contact with the n-type diffusion layer 12, forming agrid electrode 14. In this manner, asolar cell element 1 having the passivation film formed as apassivation layer 13 by the film-formingdevice 2 was obtained. - In the present example, a
solar cell element 1 was produced under exactly the same conditions as those in Example 1, except that the inputting power of the lowfrequency power source 26 was set at 1000 W. - In the present example, a
solar cell element 1 was produced under exactly the same conditions as those in Example 1, except that a passivation film was formed using the film-formingdevice 3 shown inFIG. 3 . - In the present example, a
solar cell element 1 was produced under exactly the same conditions as those in Example 3, except that the inputting power of the lowfrequency power source 26 was set at 1000 W. - The lifetimes of the
solar cell elements 1 obtained in Examples 1 to 4 were measured with a lifetime measuring device (produced by KOBELCO Research Institute, Inc.) using the microwave photoconductivity decay method. The results of the measurements are shown inFIG. 4 . - As shown in
FIG. 4 , when the inputting power of the lowfrequency power source 26 was 1000 W, the device shown inFIG. 2 and the device shown inFIG. 3 both presented lifetimes of almost 2000 μs. In the case of 500 W, the film-formingdevice 2 shown inFIG. 2 and the film-formingdevice 3 shown inFIG. 3 both presented lifetimes in excess of 2000 μs, but the lifetime was slightly higher with the film-formingdevice 3 shown inFIG. 3 . Usually, the lifetime of a solar cell element is of the order of 1000 μs, so that the results on the film-formingdevice 2 shown inFIG. 2 and the film-formingdevice 3 shown inFIG. 3 were both improved, i.e., lengthened, as compared with the value of the conventional solar cell element. - In the present embodiment, therefore, the high
frequency power source 25 and the lowfrequency power source 26 were provided and, with a high frequency voltage and a low frequency voltage being applied, the passivation film was formed. Consequently, a passivation film of satisfactory film quality could be formed, whereby the lifetime of the solar cell element could be increased. - In the present example, passivation films were formed using the film-forming
device 3 shown inFIG. 3 , with the inputting power of the lowfrequency power source 26 being varied, whereafter solar cell elements were prepared. That is,solar cell elements 1 were prepared under exactly the same conditions as those in Example 3, except that the inputting powers of the low frequency power source were set at 0 W, 500 W and 1000 W, respectively, in forming the passivation films. - The lifetimes of the resulting solar cell elements were measured by the microwave photoconductivity decay method. The results of the measurements are shown in
FIG. 5 . - As shown in
FIG. 5 , when the inputting power of the lowfrequency power source 26 was 500 W, the lifetime was the longest, exceeding 2500 μs. The lifetime was longer when the inputting power of the lowfrequency power source 26 was 1000 W, than when it was zero, namely, when the lowfrequency power source 26 was not provided; that is, the lifetime was 2000 μs. Based on these results, when the inputting power of the lowfrequency power source 26 was 250 to 1000 W, namely, when the inputting power of the lowfrequency power source 26 was about 16 to 67% of the inputting power of the highfrequency power source 25, the lifetime exceeded 2000 μs. Particularly, when the inputting power of the lowfrequency power source 26 was 900 to 700 W, namely, when the inputting power of the lowfrequency power source 26 was about 26 to 45% of the inputting power of the highfrequency power source 25, the lifetime exceeded 2500 μs, providing better results. - In the present example, passivation films were formed, and solar cell elements were produced, under the same conditions as those in Example 3, except that the inputting power of the high
frequency power source 25 was changed, and the inputting power of the lowfrequency power source 26 was changed. That is,solar cell elements 1 were prepared under exactly the same conditions as those in Example 3, except that the inputting power of the highfrequency power source 25 was set at 3500 W, while the inputting powers of the lowfrequency power source 26 were set at 500 W, 1000 W, 1500 W and 1900 W, respectively. - The lifetimes of the
solar cell elements 1 obtained in Example 6 were measured by the microwave photoconductivity decay method. The results of the measurements are shown inFIG. 6 . - As shown in
FIG. 6 , when the inputting power of the low frequency power source was 1000 W, the lifetime was the longest, exceeding 3000 μs. When the inputting powers of the lowfrequency power source 26 were 1500 W and 1900 W, the lifetimes were of the order of 1000 μs. Based on these results, when the inputting power of the lowfrequency power source 26 was 500 to 1500 W, namely, when the inputting power of the lowfrequency power source 26 was about 14 to 37% of the inputting power of the highfrequency power source 25, the lifetime exceeded 2000 μs. Particularly when the inputting power of the lowfrequency power source 26 was 550 to 1200 W, namely, when the inputting power of the lowfrequency power source 26 was about 15 to 34% of the inputting power of the highfrequency power source 25, the lifetime exceeded 2500 μs, providing better results. - The results of Examples 5 and 6 show that the inputting power of the low
frequency power source 26 was preferably about 14 to 37% of the inputting power of the highfrequency power source 25, and that the inputting power of the lowfrequency power source 26 was particularly preferably about 26 to 34% of the inputting power of the highfrequency power source 25. - In the present example, a passivation film comprising a silicon nitride film was formed in exactly the same manner as in Example 1, except that the following changes were made: SiH4 flow rate: 3000 sccm, NH3 flow rate: 1800 sccm, and N2 flow rate: 2500 sccm.
- In the present example, a passivation film comprising a silicon nitride film was formed in exactly the same manner as in Example 7, except that the inputting power of the low
frequency power source 26 was changed to 1000 W. - In the present example, film formation was performed under exactly the same conditions as in Example 7, except that the film-forming
device 3 was used. Then, the thickness of the film was measured. - In the present example, film formation was performed under exactly the same conditions as in Example 8, except that the film-forming
device 3 was used. Then, the thickness of the film was measured. - The film obtained in each of the Examples was measured for film thickness with an ellipsometer (ESM-3000AT, ULVAC, Inc.). The measured film thickness was divided by the film-forming time to determine the film-forming speed. The results are shown in
FIG. 7 . - As shown in
FIG. 7 , even under the same film-forming conditions, the film-forming speed was higher when the film was formed using the film-formingdevice 3 than when the film was formed using the film-formingdevice 2. Hence, it was found that a high frequency voltage and a low frequency voltage were preferably applied to theshower plate 23, as in the film-formingdevice 3. - The passivation film obtained by the film-forming method and the film-forming device in the present embodiment can be utilized, for example, as a passivation film of an organic EL device or the like, but is preferably used as a passivation film of a solar cell element, as in the present embodiment.
- The present invention can be utilized in the field of production of a solar cell element.
-
-
- 1 Solar cell element
- 2 Film-forming device
- 3 Film-forming device
- 11 P-type semiconductor substrate
- 12 N-type diffusion layer
- 13 Passivation layer
- 14 Grid electrode
- 15 BSF layer
- 16 Back electrode layer
- 16 a First back electrode layer
- 16 b Second back electrode layer
- 21 Vacuum chamber
- 22 Mounting stand
- 23 Shower plate
- 24 Gas introduction means
- 24 a, 24 b, 24 c Gas source
- 24 d Gas introduction pipe
- 24 e Valve
- 24 Gas introduction means
- 25 High frequency power source
- 26 Low frequency power source
- S Film-forming object
Claims (6)
Applications Claiming Priority (3)
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JP2008335051 | 2008-12-26 | ||
JP2008-335051 | 2008-12-26 | ||
PCT/JP2009/071767 WO2010074283A1 (en) | 2008-12-26 | 2009-12-28 | Film-forming device and film-forming method for forming passivation films as well as manufacturing method for solar cell elements |
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Publication Number | Publication Date |
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US20110294256A1 true US20110294256A1 (en) | 2011-12-01 |
US8735201B2 US8735201B2 (en) | 2014-05-27 |
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US13/142,138 Active 2030-05-04 US8735201B2 (en) | 2008-12-26 | 2009-12-28 | Film-forming method for forming passivation film and manufacturing method for solar cell element |
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US (1) | US8735201B2 (en) |
EP (1) | EP2381483B1 (en) |
JP (1) | JP5520834B2 (en) |
KR (1) | KR20110101223A (en) |
CN (1) | CN102265407B (en) |
MY (1) | MY155992A (en) |
TW (1) | TWI463687B (en) |
WO (1) | WO2010074283A1 (en) |
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CN104103717A (en) * | 2014-06-30 | 2014-10-15 | 浙江晶科能源有限公司 | Preparation method of antireflective film of novel solar cell |
US8952338B2 (en) | 2010-09-22 | 2015-02-10 | Kobe Steel, Ltd. | Crystalline quality evaluation apparatus for thin-film semiconductors, using μ-PCD technique |
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JP5882801B2 (en) * | 2012-03-16 | 2016-03-09 | 株式会社神戸製鋼所 | Semiconductor crystallinity evaluation apparatus and method |
US20140158192A1 (en) * | 2012-12-06 | 2014-06-12 | Michael Cudzinovic | Seed layer for solar cell conductive contact |
JP2019517142A (en) * | 2016-05-17 | 2019-06-20 | アメリカ合衆国 | Damage-free plasma CVD passivation of AlGaN / GaN high electron mobility transistors |
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JPH08339992A (en) * | 1995-06-13 | 1996-12-24 | Toshiba Corp | System and method for forming thin film |
JPH09298193A (en) * | 1996-05-08 | 1997-11-18 | Fuji Film Micro Device Kk | Manufacture of passivation film |
US20050189015A1 (en) * | 2003-10-30 | 2005-09-01 | Ajeet Rohatgi | Silicon solar cells and methods of fabrication |
US20060019477A1 (en) * | 2004-07-20 | 2006-01-26 | Hiroji Hanawa | Plasma immersion ion implantation reactor having an ion shower grid |
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US8952338B2 (en) | 2010-09-22 | 2015-02-10 | Kobe Steel, Ltd. | Crystalline quality evaluation apparatus for thin-film semiconductors, using μ-PCD technique |
CN104103717A (en) * | 2014-06-30 | 2014-10-15 | 浙江晶科能源有限公司 | Preparation method of antireflective film of novel solar cell |
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JPWO2010074283A1 (en) | 2012-06-21 |
CN102265407B (en) | 2014-02-05 |
EP2381483A1 (en) | 2011-10-26 |
WO2010074283A1 (en) | 2010-07-01 |
US8735201B2 (en) | 2014-05-27 |
KR20110101223A (en) | 2011-09-15 |
JP5520834B2 (en) | 2014-06-11 |
EP2381483A4 (en) | 2013-09-04 |
CN102265407A (en) | 2011-11-30 |
TW201034231A (en) | 2010-09-16 |
TWI463687B (en) | 2014-12-01 |
MY155992A (en) | 2015-12-31 |
EP2381483B1 (en) | 2014-12-10 |
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